The present invention relates to the mounting of a motor-vehicle wheel-hub bearing.
Known examples of the mounting of a motor-vehicle wheel-hub bearing are shown in FIGS. 2, 3 and 4 of the appended drawings. With reference to these drawings, a bearing, generally indicated 1, comprises a radially inner ring 2 and a radially outer ring 3 which have two races for respective sets of balls 4. The inner ring 2 is mounted on a hub 5 provided with a flange 6, to which a disc of the brake 7 (shown in FIGS. 3 and 4) and a wheel 20 of the motor-vehicle (shown partially in FIG. 4) are connected rigidly in known manner.
The outer ring 3, which has an outer cylindrical surface 8, is force-fitted with radial interference in a cylindrical seat 9 provided in a suspension strut 10. The ring is locked axially, in one direction, by abutment against a shoulder 11 formed in the strut 10 and, in the other direction, by a mechanical retaining system.
In the embodiment of FIG. 2, the bearing 1 is inserted in the cylindrical seat 9 from the outside (that is, from the side of the strut facing towards the wheel) until an axially inner lateral surface 12 of the outer ring 3 is brought into abutment against the shoulder 11. The ring 3 is locked axially in the opposite direction (that is, towards the outside), in this case, by the abutment of an axially outer lateral surface 13 thereof against a cover 14 screwed to the strut 10.
In the mounting of FIG. 3, on the other hand, the bearing 1 is inserted in the cylindrical seat 9 from the inside (that is, from the side of the strut facing the chassis of the vehicle) until the axially outer lateral surface 13 of the outer ring 3 is brought into abutment against the shoulder 11 which, in this case, is formed at the level of the outer surface of the strut 10. The ring 3 is locked axially in the opposite direction (that is, towards the inside) in this case by the abutment of its axially inner lateral surface 12 against a snap ring 15 inserted into a groove 16 formed in the cylindrical seat 9 of the strut 10.
These conventional solutions have a series of disadvantages such as:                large axial size which leads to an excessive offset both of the brake disc and of the wheel, thus penalizing their operation,        a high mounting cost due both to a larger amount of material of the strut as well as the presence of the above-mentioned mechanical retaining systems (the snap ring and its seat in one case, and the cover and its fixing members in the other case), and to the greater cost of performing the mounting operation,        the impossibility to control the axial preloading of the bearing and hence to optimize its fatigue life since, for reasons of mounting tolerance, the outer ring 3 is necessarily inserted between the two axial abutment surfaces (the shoulder 11 on one side, and the cover 14 or the snap ring 15 on the other) with play, and        the possibility of axial movements of the bearing, precisely because of the mounting with axial play, which movements produce an annoying noise (a so-called clicking noise).        
A further known example of the mounting of a motor-vehicle wheel-hub bearing is provided by French patent application FR-2 800 234 from which FIG. 4 of the appended drawings is taken. According to the teaching proposed in this patent application, the outer ring 3 of the bearing is locked, on the axially inner side, against the shoulder 11 of the cylindrical seat 9 of the strut 10 and, on the axially outer side, against a radially inner rim 18 formed by cold plastic deformation.
However, this further solution has the disadvantage that it cannot oppose any relative movements between the outer ring of the bearing and its seat in the strut caused by the different thermal expansions of the bearing and of the seat when the strut is made of light alloy.